FIG. 6 shows a simplified drawing of a wheel loader which is one of construction machines to which the present invention pertains. The wheel loader as shown in FIG. 6 operates the work equipment 52 by converting the engine power into the hydraulic power, and travels by transmitting the engine power to the drive wheels 70 via the transmission. This wheel loader is often used for loading the pile such as earth and sand into the dump truck.
For this type of construction machine, large driving force of drive wheels for excavating and scooping (hereinafter referred to as “driving force”) as well as sufficient acceleration and speed during carrying the earth and sand are required.
The operator carries out various operations such as loading operation while controlling the engine speed by adjusting the accelerator (accelerator pedal). More specifically, when large driving force is necessary for excavating and scooping, or prompt acceleration is required, the operator largely steps on the accelerator to obtain sufficient engine power. Additionally, when high speed is necessary, the operator largely steps on the accelerator to obtain the high engine speed.
On the other hand, for this type of construction machine, in order to improve the fuel efficiency, there has been proposed a construction machine that is enabled to switch a first mode in which the maximum engine speed is set to a prescribed engine speed and a second mode in which the engine speed is limited to an engine speed less than such prescribed engine speed to realize better fuel efficiency. When the operator selects the second mode, performance of acceleration and maximum traveling speed is sacrificed to some degree, but the fuel efficiency during the operation becomes better than that in the first mode. It should be noted that there is Patent Literature 1 that provides similar technique to the above-stated technique.
Patent Literature 1: Japanese Patent Application Laid-open No. 2004-190615